A 34-year-old Chicago native, wanted by Fairfax County police for what a prosecutor has called the "unbelievably brutal murder" of a 63-year-old Pimmit Hills widow, was arrested yesterday by Tampa, Fla., police.

Detectives said Richard Lee Whitley is charged with murder in the July 28 death of Phoebe Parsons, who was stabbed and beaten to death in the bedroom of her Northern Virginia home.

Whitley, who had lived next door to Parsons for several months prior to the murder, also was being held without bond for questioning by Florida police in connection with the roadside slayings of four people in the Holmes Beach area Aug. 1.

Fairfax County prosecutor Robert F. Horan Jr. yesterday described Parsons' murder as one of the most brutal in a recent series of murders in the county. He said the county asked the FBI to join in the search for Whitley after the police noticed that Parsons' automobile and credit cards were missing.

Whitley, whom Fairfax police said was unemployed, was arrested without incident at a home in the Hyde Park section of Tampa, according to John Barker, a police spokesman there. He was unwilling to release details on how authorities located the suspect.

Parsons' late-model Volkswagon had been found abandoned outside Okeechobee, Fla., 200 miles south of Tampa, on Aug. 1, said Tampa FBI agent Dick Ross.

Tampa police spokesman Barker said in a telephone interview yesterday that Whitley also was being questioned as a possible suspect in the slayings of Tampa pediatrician Dr. Juan Dumois, his two sons and an onlooker, who were shot and killed by a hitchhiker. A fifth person injured in the shootings has given police a description of the gunman, Barker said.

Robert Barrows, recovering from a head wound received during the Homes Beach shootings, told a Tampa newspaper that Dumois had picked up the hitchhiker shortly before the shootings.

"We had offered him a ride and had pulled back onto the highway when it happened," Barrows said. "I think he's crazy mad at somebody."